Blast Resistant Shelter

ABSTRACT

A blast resistant shelter apparatus includes a framework having at least an upper metal rail. A plurality of metal panels each have a C-shaped cross-section defined by a central flat web and two channel arms on the opposite sides of the central flat web. The metal panels are vertically mounted within the framework in a side by side relationship to define a wall. Each panel includes an upper and a lower end plate. A metal interior wall cladding is connected to the panels and spans the channel arms of each panel to close the cross-sections of the panels to define an interior space of each panel. The upper metal rail and the upper end plate of each panel have aligned fill openings defined therethrough for introducing a particulate material such as sand into the interior space of the associated panel.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a Non-Provisional Utility application which claimsbenefit of co-pending U.S. Patent Application Ser. No. 60/879,756 filedJan. 10, 2007 entitled “Blast Proof Shelter” which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to blast resistant shelters, andmore particularly, but not by way of limitation, to a blast resistantshelter of modular construction which serves as a safe harbor forpersonnel in hostile military or terrorist-prone areas.

2. Description of the Prior Art

Historically field shelters for military combat operations have involvedthe use of sand bags arranged in a wall-like pattern around varioustemporary structures. Such sand bagged fortifications are laborintensive to construct, and have the disadvantage of being non-moveableand non-reusable.

U.S. Pat. No. 3,820,294 to Parker has proposed the use of modularconstructed walls filled with sand for such field emplacements. Althoughthe Parker system can be disassembled and reused, it is not capable ofhaving the sand removed from the assembled structure so that it can beeasily transported for reuse without disassembly of the assembledstructure. The structure disclosed by Parker is focused on improvementof resistance to bullet penetration, and there is no discussion of blastresistance. There is also no indication that the walls constructed ofplastic or plastic/woven material board and slotted connectors wouldprovide any improvement in flexural dynamics characteristics that wouldimprove its blast resistance.

Another approach to blast resistant shelters is seen in U.S. Pat. No.6,412,321 to Palatin which provides for the construction of hollow wallswhich are then poured full of concrete to create a rigid permanentnon-moveable blast resistant structure. Palatin's structure also suffersfrom the disadvantage of not being moveable to a new location.Furthermore, its rigid concrete walls do not provide the ductilitynecessary for absorbing blast forces by yielding without failure.

Structures have also been proposed for containing blast forces withinthe structure. An example of such a structure is seen in U.S. Pat. No.3,832,958 to Hiorth which provides a building for containing explosivedangerous materials. The Hiorth structure provides two concentriccylindrical shells defining an annular cavity which is filled with sand.The Hiorth structure is not designed for relocation and reuse.

Also, the structures discussed above are not applicable to use withinexisting building structures or in combination with existingconventional building structures such as office buildings or the like.

The prior art also includes a number of modular constructions for stormshelters and/or security shelters which can be constructed eitherfree-standing or within an existing building. One such structure is thatshown in Waller U.S. Pat. No. 5,813,174 which provides a modularstructure made from a steel framework and steel panels received withinthe framework. The structure can be assembled either free-standing orwithin an existing building to provide a security enclosure or as astorm shelter for protection from tornados and the like. The structureof the Waller '174 patent is designed more for protection againstprojectile impact and storm forces, and not for blast resistance toexplosions. The Waller '174 structure does not utilize any sand fill orother particulate fill in the structure walls.

Also, U.S. Pat. No. 6,393,776 to Waller et al. discloses a modifiedversion of the Waller '174 structure particularly designed as a tornadoshelter for placement on a concrete foundation which utilizes a tubstructure to form a part of the shelter. Again, the Waller '776structure does not include any sand fill or other particulate fill inthe structure walls.

Perhaps the best indication of the continuing need for the developmentof improved blast resistant structures is the recent solicitation by theU.S. government for proposals for new designs for blast andfragmentation resistant shelters to be utilized in high threatlocations. That solicitation identified as “R2190 Blast andFragmentation Resistant Construction” dated Mar. 3, 2006 reads asfollows:

“Design, develop, model, and test an expeditionary construction methodfor blast and fragmentation resistant structures for high threatlocations and forward operating bases. The construction method shoulduse stay-in-place forms filled with a mixture of cement and indigenousmaterials or equivalent approach to create a structural framework withinherent blast and fragmentation protection capabilities. Protectionshould be provided for the exterior walls and roof, and includeprovisions for incorporating protective windows and doors in thebuilding system. Detailed design drawings shall be developed for barracktype structures approximately 20 ft by 40 ft in plan, and allow modularconstruction for larger units. The structural framework must belightweight to allow expedient air/sea transport, use material with highstrength and ductility for blast resistance, achieve a final cost nogreater than two times that of existing unprotected facilities, and beable to be erected in theater using local minimally-skilled labor. Thedesign shall mitigate flammability and other life-safety issues relatedto military construction. Documentation for the final product mustinclude: 1) a field manual detailing the construction method and avalidated engineering level design model for determining resistance toblast threats; 2) a detailed technical report describing the results ofappropriate laboratory component testing and full-scale blastexperiments that validate the performance of the structures constructedusing this method; and 3) participation with TSWG in the preparation ofdocumentation that validates the construction process, cost estimate,mechanical properties of the stay-in-place forms and hazard reductionresulting from the full scale blast testing. This information will beimplemented to a Unified Facilities Criteria document as maintained bythe U.S. Army Corps of Engineers, Protective Design Center.”

Thus it is seen that there is a continuing need for the development ofsuch blast and fragmentation resistant structures.

SUMMARY OF THE INVENTION

The present invention provides a light-weight steel blast proof shelterstructure which includes individual fabricated tubular steel andcold-formed, light gauge, cold rolled steel components which arecompactly packaged and shipped loose with connecting hardware andstructural adhesive. The components are assembled at the site by the enduser to form a rectilinear frame and wall assembly with steel sheet, ofvarying thicknesses, bonded to exterior and interior faces of walls, andinterior faces of roofs which require blast, fragmentation, and smallarms fire terminal ballistics protection (fortified walls, roof).

Continuity of individual modular components is achieved by assemblingtubular components with sleeve inserts and steel keys in slotted tonguesinserted through rectangular holes in connected tubes and by bonding andconnecting light gauge steel components with viscoelastic structuraladhesive and sheet metal screws to like components and tubularcomponents. Rectilinear tubular steel framing forms the constructionskeleton for assembly of the remainder of the structure or structuralmodule and forms the edges and corners of the structural unit. Tubularsteel elements which lie along the tops of walls have circular holes intop and bottom walls which match holes of the same size in thecold-formed steel end brackets which connect modular wall panels.Interior light gauge steel sheets are bonded and screwed to the insideface of fortified walls, creating cavities in the walls which are formedby the closed channels. After assembly and final positioning of thestructure or structural modules, sand or a sand-cement mixture,depending on whether the assembly is to be relocated or is a permanentinstallation, is introduced into the cavities of the walls which are tobe fortified. Similar holes located in bottom tube components and bottompanel end brackets permit sand to be evacuated by lifting the fortifiedwall of the unit before structural units are relocated. Blast proofshelters which are to be permanently located at a site and which are tobe anchored to concrete floor slabs for stability have holes in thebottom end brackets of wall panels, whether walls are fortified or not,which permit connection of the walls to concrete slabs using adhesive orexpansion anchors and concrete screws. This construction provides forthe support and attachment to interior, non-fortified walls of gypsumboard, vinyl sheets, or wood panels. The installation of interior wallelectrical outlets, switches, and fixtures, and attachment of airhandling ducts to protected vent openings is also accommodated.

The rectilinear blast proof shelter may serve as a stand-alone shelterwith four fortified walls and roof or may become a modular component ofa larger shelter structure including an assemblage of two or morerectilinear modules whose exterior walls and roof are fortified toresist blast, fragmentation, and small arms fire. Interior walls ofassemblages of individual modular components, although not required tobe fortified, may be required to provide lateral resistance against theforces produced by blasts.

Cold-formed steel floor panels, which are required for structures orstructural modules which will be relocated and which are not anchoredpermanently to concrete floors, are assembled in a manner similar to thewall panels and are of similar configuration. Floor panels, which areoriented with the open channel and flanged channel ribs facing up, arefloored with wood panels or lumber to provide a walking surface. Thefloor decking is bonded and screwed to floor panel ribs. Sand orsand-cement infill is not used for the floor structure.

Cold-formed steel roof panels, where required, and their adhesive-bondedpanel end brackets are assembled similar to floor panels, with openchannels and flanged channel ribs facing down. Light gauge steel sheetsare bonded and screwed to channel flanges of roof panels for fortifiedroofs. Sand or sand-cement infill is not placed in the cavities of theroof structure. Where terminal ballistics protection of the roof isrequired, sandbags may be placed on top of the roof and around protectedopenings in the roof. Selected modular panels of the roof, althoughsimilar in configuration to the wall and floor panels, are fabricatedwith protective openings which permit attachment of air handling ducts,electric power, communications, and other utilities to the roof surface.

This system also provides modular, welded, cold-formed steel dooropening modules which are erected to the tubular steel skeletal frame inlieu of a fixed number of channel-shaped wall panels. Door modules areconnected to tubular frames with adhesive and screws or they areconnected to concrete floor slabs with adhesive or expansion anchors andconcrete screws. Door opening modules located in fortified walls arefilled with sand or sand-cement mixtures similar to fortified wallpanels. Rough openings in door opening modules permit installation of avariety of blast and bullet-resistant doors. The system further providesfor modular, welded, cold-formed steel window opening modules, erectedsimilar to door opening modules, which permit installation of a varietyof blast and bullet-resistant windows.

Blast proof shelters may be employed as stand-alone buildings or theymay be constructed within new or existing buildings, including at upperfloors, to provide blast and terminal ballistics protection to buildingoccupants and equipment.

Blast walls, constructed and erected in a manner similar to thosecomprising blast walls in a blast proof shelter, may be erected andattached to building exteriors to create blast and terminal ballisticsprotective curtain walls.

In one embodiment the blast resistant shelter apparatus of the presentinvention can be summarized as comprising a framework including at leastan upper metal rail. A plurality of metal panels, each panel having aC-shape cross-section defined by a central flat web and two channel armson opposite sides of the central flat web are vertically mounted withinthe framework in side by side relationship to define a wall. Each panelincludes an upper end plate. A metal interior wall cladding is connectedto the panels and spans the channel arms of each panel to close thecross-sections of the panels to define an interior space of each panel.The upper metal rail and the upper end plate of each panel have alignedfill openings defined therethrough for introducing a particulatematerial such as sand into the interior space of the associated panel.

In another embodiment of the invention a blast resistant shelterapparatus includes a framework including at least an upper rail. Aplurality of panels, each panel having an enclosed interior space, arevertically mounted within the framework in a side by side relationshipand attached to each other and the upper rail to define a wall. Aparticulate material such as sand is received in the interior space ofeach panel of the wall. The wall preferably has a mass to stiffnessratio in the range of from about 0.03 to about 0.05 lb-sec²/psi.

A plurality of room structures constructed in accordance with thepresent invention may be assembled together and covered with a tentenclosure. Such a construction provides a blast resistant shelterapparatus including a plurality of six-sided room structures arranged ina pattern to define a multi-room building. Each of the room structureshas four room walls. Each of the room walls includes a plurality ofpanels vertically mounted in a side by side relationship to define therespective room wall. Each panel has an enclosed interior space. Aparticulate material such as sand is received in the interior spaces ofthe panels of at least some of the room walls to make thoseparticulate-filled room walls blast resistant. A tent enclosure isarranged over the structures to define an attic space of the buildingwhich may receive utility connections and the like for the building.

In another embodiment of the invention a blast resistant shelterapparatus is provided which can be constructed within the interior of anexisting building of conventional design. Such a blast resistant shelterapparatus includes a building having a plurality of structural exteriorwalls. A blast resistant interior wall is located within the buildingand spaced inwardly from the exterior walls. The interior wall has ahollow wall space and has a majority of the hollow wall space filledwith a particulate material having a density of at least 90 pounds percubic foot. At least one laterally extending interior support wall isconnected to the blast resistant interior wall.

In another embodiment of the invention a blast resistant perimetercurtain construction is provided as a cladding for the exterior of abuilding otherwise of generally conventional structure. Such a blastresistant shelter apparatus includes a building having a foundation anda structural framework extending upward from the foundation. A blastresistant perimeter curtain is supported from the framework and at leastpartially defines a perimeter wall of the building. The curtain is ofmodular construction including a plurality of side by side verticallyoriented metal panels, each panel having a hollow interior panel spacehaving a width and a height greater than the width. At least themajority of the interior panel space is filled with a particulatematerial such as sand or sand-cement mixture.

Accordingly it is an object of the present invention to provide animproved blast resistant shelter apparatus.

Another object of the present invention is the provision of a blastresistant shelter apparatus which can be rapidly assembled from modularcomponents in the field and then filled with a particulate material suchas sand.

Still another object of the present invention is the provision of ablast resistant shelter apparatus having particulate filled walls whichcan be emptied to allow for ease of relocation of the shelter apparatus.

Still another object of the present invention is the provision of ablast resistant shelter apparatus having walls constructed in a mannerto provide high ductility for absorption of blast forces without failureof the wall structure.

Still another object of the present invention is the provision of ablast resistant shelter apparatus providing a combination of alightweight hollow metal wall construction assembled with viscoelasticadhesives so as to provide a highly ductile metal shell, which can thenbe filled with high density sand to provide a high density blastresistant wall structure which is still highly ductile for absorbingblast forces.

Still another object of the present invention is the provision of ablast resistant shelter apparatus which can be assembled into amulti-room structure and covered with a tent structure to provide anattic space for provision of utilities and the like to the building.

Still another object of the present invention is the provision of ablast resistant shelter apparatus which can be rapidly constructedwithin the interior of a conventional building either as a retrofit oras part of new building construction.

Still a further object of the present invention is the provision of ablast resistant shelter apparatus which can be constructed as aperimeter curtain on the exterior of a building.

Other and further objects features and advantages of the presentinvention will be readily apparent to those skilled in the art upon areading of the following disclosure when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-5 show the sequence of assembly of the tubular frame of theblast proof shelter.

FIG. 6 is a perspective view of the connection of the top tubular steelframe assembly to the bottom tubular steel frame assembly via theinserted steel sleeves.

FIG. 7 is a perspective view of the connector for connecting tubularframe elements.

FIG. 8A is a cross sectional view taken along the line 8A-8A of FIG. 7.

FIG. 8B is a cross sectional view taken along the line 8B-8B of FIG. 7.

FIG. 9 shows in perspective view a snap-in bent plate panel endconnector fitted into one end of a C-shaped panel.

FIG. 10 is a perspective view of a portion of the tube assembly withwall and floor panels connected at a corner of the enclosure.

FIG. 11 is a perspective view in partial cross section of the assembledenclosure illustrating a roof panel and a door frame module.

FIG. 12 is an exterior view, in perspective, of the completely assembledenclosure except the door and the exterior wall blast shield.

FIG. 13 is an exterior view, in perspective, of the completely assembledenclosure except the door and with the exterior wall blast shieldinstalled.

FIG. 14 is a floor plan of a multi-room blast proof shelter assembly,assembled from individual shelter assemblies.

FIG. 15 is an exterior side view of the shelter assembly of FIG. 14.

FIG. 16 is perspective view of a bottom tube and wall panel illustratingthe connection of the bottom panel end bracket connection to a concreteslab.

FIG. 17 is a sectional view through the roof and top of a wall of ashelter taken along line 17-17 of FIG. 13.

FIG. 17A is a cross-sectional view of a portion of the wall taken alongline 17A-17A of FIG. 17, with no sand shown in the panel cavities, so asto show the arrangement of the various steel channels and sheets makingup the wall structure.

FIG. 18 is a roof plan view of the shelter assembly of FIG. 14 showing afabric tent enclosure and support framing attached to the shelterassembly.

FIG. 19 is a perspective view of the shelter assembly of FIG. 18 showingthe supported fabric tent.

FIG. 20A is an exterior side view of the shelter assembly and fabrictent of FIG. 18.

FIG. 20B is a cross sectional view through the shelter assembly andfabric tent of FIG. 18, taken along line 20B-20B of FIG. 20A.

FIG. 21 is an exterior end view of the shelter assembly and fabric tentof FIG. 18.

FIG. 22 shows a first floor plan of a building with a built-in assemblyof blast shelters.

FIG. 23 shows a second and third floor plan of the building and built-inblast shelters of the building shown in FIG. 22.

FIG. 24 is a cross sectional view through the building and built-inblast shelters of FIGS. 22 and 23.

FIGS. 25A and 25B illustrate the unassembled modular panels, tubeassemblies, and sheet steel positioned for compact packaging.

FIG. 26 shows a wall section through a blast and bullet proof, exteriorcurtain wall installed between the first floor slab and second floorframing of a building.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to FIG. 13, a perspective view is thereshown of oneembodiment of a blast resistant shelter apparatus generally designatedby the numeral 100. The apparatus 100 is in the form of a six-sidedfree-standing structure having four walls, a ceiling and a floor asfurther described below. A door opening 101 is provided in one wall.

The shape of the apparatus 100 is generally determined by a skeletalstructural framework 102 as shown in FIG. 4.

The framework 102 includes four vertical members or corner posts 104,106, 108 and 110, four upper rails 112, 114, 116 and 118, and four lowerrails 120, 122, 124 and 126.

Each wall of the apparatus 100 includes a plurality of metal panels 128connected between an associated pair of the upper and lower rails. Theconstruction of the panels 128 is best shown in FIG. 9. Each panel 128has a C-shape cross-section defined by a central flat web 130 and twochannel arms 132 and 134 on opposite sides of the central flat web 130.Panels 128 are preferably made of cold formed light gauge steel sheets.Each panel 128 includes two channel fingers 136 and 138 extending towardeach other from the channel arms 132 and 134.

Upper and lower end plates 140 and 142, respectively, are assembled withthe panels 138 to close the upper and lower ends of the channel thereof.

As best seen in FIGS. 10-12 a plurality of the metal panels 128 arevertically mounted within the framework 102 in side by side relationshipto define each of the walls of the apparatus 100. A typical wall isshown in elevation cross-section in FIG. 17, and in horizontalcross-section in FIG. 17A.

A metal interior wall cladding 144 is connected to each of the panels128 and spans the channel arms 132 and 134 of each panel 128 to closethe cross-sections of the panels to define an interior space 146 of eachpanel. A metal exterior blast shield 148 is attached to the central flatwebs 130 of the panels 128.

Each of the upper rails such as 116 has fill openings 150 and 152therethrough which are aligned with a fill opening 154 of the upper endplate 140 of each panel 128 for introducing a particulate material 156into the interior space 146 of the associated panel 128.

As best seen in FIG. 9, the lower end plate 142 of each panel 128 mayhave a drain opening 158 defined therein for draining the particulatematerial 156 from the interior space 146.

Similarly drain openings 160 and 162 are located in each of the lowerrails as shown in FIG. 10 and are aligned with the drain openings 158 ineach of the bottom end panels 142. The drain openings 158, 160 and 162permit the particulate material to drain out of the interior space whenthe structure 100 is lifted up off of the ground surface, thus greatlyreducing the weight of the structure 100 so that it can be more easilyrelocated to a new location.

Applicant's blast resistant shelter apparatus 100 is packaged andshipped as a compact assembly of unassembled, prefabricated componentsfor on site erection and assembly. FIGS. 25A and 25B show theunassembled modular panels and the tube assemblies positioned forcompact packaging and shipment. The U-shape tube assemblies 160, 162,180, 182 have spacing between vertical legs such as 166 and 164 whichare slightly larger than the length of modular panels 128. This permitspackaging of panels 128 lying between the legs of the tube assembly.FIG. 25B shows a bottom layer of modular panels 128 on top of which asecond layer of inverted modular panels 128 has been placed so that thetwo layers occupy nearly the same thickness as a single layer of panels.Prefabricated U-shape tube frames assemblies 160, 162, 180, 182 createthe perimeter of the package and provide protection of corners of thebundle for shipment. A single layer of the above-described packagedcomponents is shown in FIG. 25B lying on top of flat sheets of lightgauge steel which comprise the exterior blast shield 148 or wallinterior steel sheets 144. The compactness of the packaged sheltermaterials provides economy for shipping and protection of the palletizedpackage.

FIGS. 1-5 illustrate the sequence of assembly of the framework 102 ofthe apparatus 100 to which the modular components of the walls, floor,roof and door opening modules are later attached. This framework 102provides a tubular skeleton for the blast resistant shelter apparatus100 and is constructed of preformed, welded tubular elements.

FIG. 1A shows two U-shaped welded tube assemblies 160 and 162 whichinclude lower rails 124 and 120 which are welded to vertical postportions such as 164 and 166 which define the lower portions of thevertical members such as 108 and 106 seen in FIG. 4. Light gauge steelsleeve connectors 168 are received in the upper ends of the verticalpost portions such as 164 and 166 and in the lower ends of the verticalpost portions such as 184 and 186. As seen in FIG. 6, laser cut halfmoon stops 170 limit the insertion of the sleeve connectors 168.

The other two lower rails 122 and 126 are straight tube elements whichare connected between the U-shaped assemblies 160 and 162 as seen inFIGS. 1B and 2B.

FIG. 2B shows the assembled lower U-shaped assemblies 160 and 162 withthe lower rails or straight tube elements 122 and 126.

Then, upper U-shaped assemblies 180 and 182 shown in FIG. 2A areconnected to the post members such as 164 and 166 via the sleeveconnectors 168. That assembly is shown in FIG. 3.

Then the upper rails 112 and 116 which may also be described as straighttube elements 112 and 116 are put in the locations as indicated in FIGS.4 and 5.

The straight tube elements 122, 126, 112 and 116 with the preweldedU-shaped assemblies are described with reference to FIGS. 7, 8A and 8B.

FIGS. 7, 8A and 8B show steel slotted tongue 172 and wedge shaped steelkey connector 174 which, when inserted into and firmly seated in theslotted tongue 172, provides continuity between the straight tubeelements 122, 126, 112 and 116 and the vertical arms such as 164 and 166of the U-shaped welded tube assemblies such as 160 and 162. Referring toFIGS. 8A and 8B, the straight tube section 116 is provided with a weldedsteel plate connector 176 which includes a base 178 and the slottedtongue 172. The framework 102 further includes laser cut rectangularslots which receive the slotted tongues 172 of the straight tubeelements 122, 126, 112 and 116. The key 174 is tightly wedged into theslotted tongue 172.

FIG. 6 illustrates the manner in which the lower vertical post portionssuch as 164 and 166 are connected to the upper vertical post portionssuch as 184 and 186 via the sleeve connectors 168.

After the assembly of the skeletal framework 102 as shown in FIG. 5, thepanels 128 are connected within the framework to define the walls, floorand ceiling of the apparatus 100.

The framework 102 has a plurality of laser cut screw holes 188 (see FIG.7) which align with screw holes provided in the panels 128 to aid in theassembly thereof. Similarly, utility holes 190 are provided in theframework 102 and align with utility holes such as 192 (see FIG. 9) inthe panels 128 to allow for the running of conduit and other utilitiesthrough the walls.

Once the framework 102 has been assembled to the point illustrated inFIG. 5, the wall, floor and ceiling panels 128 can be installed. FIG. 5shows wall panels 128 being assembled to the framework 102. Wall, roof,and floor panels 128 with their associated panel end brackets 140 and142 are preassembled by applying viscoelastic polyurethane adhesive tothe contact surfaces between arms 194 of the end panels 140, 142 and theC-shape modular panels 128 shown in FIG. 9. FIG. 9 illustrates in moredetailed the snap in features of the panel end brackets such as 142 tothe C-shape panel 128. Embossments 196 are provided on the arms 194 andextend outward from the panel end bracket 142 to form snaps forengagement with square holes 198 punched or otherwise preformed in thechannel arms 132 and 134 of the C-shape panels 128.

FIG. 10 is a cutaway perspective view of an inside corner of the shelterapparatus 100 midway during construction. In this view a number ofpanels 128 have been assembled with the walls of the structure, and anumber of panels 128 have been assembled into the floor of thestructure. None of the interior cladding sheets 144 or exterior blastshields 148 have yet been installed. As can be seen from FIG. 10,multiple panels 128 are connected in side-by-side relationship to formthe walls and floor for the shelter. Once the end panel brackets 140 and142 have adhesive applied and are snapped into the ends of the panels128, the panels 128 are connected to the upper and lower rails such as118 and 126 after liberally coating with adhesive the contact surfacesbetween the panels 128, the end panel brackets 140 and 142, and theskeletal framework 102 and screwing the end panel brackets 140 and 142to the skeletal framework 102 through prepunched holes in the panel endbrackets 140 and 142 and matching laser cut screw holes in the framework102. As previously noted, the upper rails and upper end brackets havealigned fill holes 150, 152 and 154 therein. The fill holes serve twopurposes. One is to permit electrical conduit to be routed through thewalls and roof of the shelter apparatus. Another purpose is to provide ameans for introducing particulate material such as sand or a sand cementmixture into the cavities of the walls after the interior claddingsheets 144 are installed. The lower end panels 142 and lower railsinclude drain holes 158, 160 and 162 such as previously described topermit the evacuation of sand when the apparatus 100 is to be relocated.

Preferably the dimensions and construction of the metal panels and thevolume of the interior space are such that the panels have a stiffnessand the interior space of each panel has a volume such that if theinterior space were filled with particulate material having a density ofapproximately 109 pounds per cubic foot, a mass to stiffness ratio ofthe panels would be in the range of from about 0.03 to about 0.05lb-sec²/psi.

While the framework 102 has been described as preferably being made fromsteel tubular members and steel channels, it will be appreciated that inits broader aspects the present invention contemplates a framework madeof materials other than steel. Any suitable material that can resistpenetration by bullets and provides the desired ductility may beutilized.

FIG. 13 is a perspective view of the apparatus 100 illustrating theplacement of the exterior blast shields 148 which are bonded withpolyurethane adhesive and screwed with self-drilling, self-tappingscrews through pre-punched holes in blast shields 148 to the outsidefaces of the assembled walls seen in FIG. 12. It should be noted thatonly those walls which will be exterior walls subject to blast requirethe blast shield 148, since the apparatus 100 may be a modular componentof a larger assembly of components such as illustrated in plan view inFIG. 14 and in side view in FIG. 15.

FIGS. 17 and 17A illustrate the attachment of the interior steel wallcladding 144 and ceiling cladding 200. These interior sheet steelcladdings are attached to the inside flanges of wall and ceiling panels128 with viscoelastic polyurethane adhesive and self-drilling,self-tapping screws through pre-punched holes in interior steel wallcladding 144 and 200. The attached interior wall cladding 144, inconnection with the open channel of the C-shape panels 128 form the wallcavities 146 into which particulate material 156 is introduced into thewalls which are to be potentially exposed to blast forces. In addition,the attached interior wall cladding 144 and ceiling cladding 200, actingcompositely with the C-shape panels 128 produce a flexural cross-sectionwhose moment of inertia (resistance to bending) and section modulus(ability to carry flexure) are substantially increased. FIG. 17 furtherillustrates the placement of particulate matter 156 into the cavities146 of the framework 102 on the exterior wall of the blast resistantshelter apparatus 100. FIG. 17 also shows the placement of sand bags 202on the roof of the apparatus 100 to provide terminal ballisticsprotection for the roof, and a protected duct or ventilation openingfeature 204 extending through the roof of the shelter apparatus 100.

Although the shelter apparatus 100 is described herein primarily withregard to its use for blast protection such as for military personnel inhostile environments, it will be appreciated that the same apparatus 100may be used for other purposes such as for a tornado or hurricaneshelter or the like.

Dynamic Testing and Ballistics Testing

The uniqueness of the composite blast wall panels is illustrated by theperformance of the panels when subjected to the following describeddynamic testing and analyses, full scale blast testing, and terminalballistics testing.

Dynamic testing was conducted on test wall panels of the blast proofshelter blast walls to determine dynamic performance when subjected toimpulse loading. A piezoelectric acceleration sensor was mounted on thetest specimen to determine accelerations, velocities, and displacementsat the mid-span of the wall panel. Test panels were tested without sandinfill in the cavities and with sand infill in the cavities. Test panelsfor each condition consisted of one 8 inch wide by 3 inch deep, 18 gaugesteel wall panel 128 sandwiched between adhesive-bonded 12 gaugeexterior blast shield 148 and 16 gauge interior steel cladding 144.Sand-filled test panels were filled with cohesionless sand 156 weighingapproximately 109 pounds per cubic foot. Tests indicated that thesand-filled blast panel, compared with the empty blast panel, haddamping factors which were approximately 12 to 13 percent greater andperiods of vibration in the fundamental mode of vibration which wereapproximately 88 percent greater. As shown by calculations set forthbelow, the mass to stiffness ratio was increased to approximately 338percent of the unfilled value by the sand infill. The significance ofthe change of dynamic characteristics will be illustrated hereinafter.

Blast tests were conducted at the HTL blast range at Tahoka, Tex. onthree 7 foot, 10 inch cubed blast proof shelters having wallsconstructed with 3 inch thick panels 128. Dimensions and gauges of blastwall material were as described for the dynamic test wall panelpreviously described. The blast wall of the nearest blast proof shelterhad a standoff distance of 20 feet from a 50 pound TNT explosivepackage. HTL reported a maximum positive transient displacement of theblast wall of approximately one inch, a maximum negative transientdisplacement of 0.4 inches, a total impulse of approximately 73.6psi-ms, and a peak reflected pressure on the blast wall of approximately14,250 pounds per square foot. There were no permanent deformations ofthe blast walls and no measurable lateral displacement of the unanchoredshelters. The measured blast pressure versus time loading was modeledinto a proprietary government blast dynamics analysis program (SDOF)using the dynamic properties of the sand-filled test wall panels andalso the dynamic properties of the unfilled test wall panels. The testwall panels without sand would have had a maximum deflectionapproximately 1.9 times that for the sand-filled test wall panels. Thetest wall panels without sand would have been stressed beyond yieldstress of the steel and would have had a residual, permanent deformationof the wall whereas the sand-filled test wall panels were found to haveno residual displacement of the wall. The results of the SDOF analysesdemonstrated the important contribution of the cohesionless sand infillin attenuating the effects of blast on the blast walls of the blastproof shelter.

Terminal ballistics tests were conducted on the 3 inch deep test blastwall panel assemblies consisting of multiple panels as described aboveto determine resistance to penetration of military small arms rounds.The test panels resisted 7.62 mm and .308 caliber military ball roundswhen shot from a distance of 15 feet. Test blast wall panels alsoresisted 21 rounds of sustained and concentrated fire of 7.62 mmmilitary ball rounds fired from a distance of 25 meters and sustainedonly one penetration after the sixteenth round.

Ductile Structures and the Mass to Stiffness Ratio

Ductility is defined as the ability of a structure or structural elementto deform easily upon the application of a load or as the ability towithstand large plastic (inelastic) deformation without rupture orfailure by instability. It is also defined as bendability and theability to undergo large deformations before fracture. The opposite ofductility is brittleness. A ductile structure which can deform andabsorb the energy of a blast without structural failure that wouldjeopardize the safety of persons within the structure is superior forblast protection purposes to a more rigid inflexible structure.

In the case of the present invention, the structure (the composite lightgauge steel wall) is ductile by virtue of its ability to undergo largedeformations without yielding and further to undergo plasticdeformations in the material yield stress range without failing. Thesand infill does not change this ductility. The sand only increases themass of the structure and also provides additional dampening ofvibrations, particularly at larger wall deformations under blast loads.One measure related to the ductility of the structure and its mass isthe “mass to stiffness ratio” which is explained below. A high mass tostiffness ratio most demonstratively improves the ability of thecombined structure and sand to resist blast forces. Increased damping offlexural systems were found from the SDOF program to result in theability of the flexural systems to be able to resist higher explosiveforces at the same standoff distance. An increased damping ratio ordamping factor results in free vibration displacements of a structuralsystem degrading more rapidly. A means of determining the damping factoris to measure the ratio of displacement amplitudes on successive cyclesof vibration. A classical theoretical logarithmic decrement function wasused to determine the damping ratio for the sand filled vs. thenon-sand-filled test panels.

Following is a sample calculation of the “mass to stiffness” ratio andrelated parameters for the panels used in the field testing describedabove.

-   -   Based on the moment of inertia of the composite steel blast        proof enclosure panel section, the mid-point deflection of the        panel under a uniform pressure load is 0.0873 inches/psi        pressure. This is the flexibility of the panel. The reciprocal        of the flexibility is the stiffness, which equals

k=1/flexibility=1/0.0873 inches/psi=11.45 psi/inch

Weight of the composite steel panel only=0.6206 lbs/in×88 inchlength=54.6128 lbs

-   -   The mass is the weight divided by gravity

m=54.6128 lbs/386 in/sec²=0.1415 lb-sec²/in

The mass to stiffness ratio=0.1415 lb-sec²/in÷11.45 psi/in =0.0124lb-sec²/psi

-   -   The fundamental frequency of a uniformly loaded beam per the        Raleigh method is

$\begin{matrix}{\omega_{f} = {\prod^{2}\lbrack {{EI}\text{/}{ml}^{3}} \rbrack^{1/2}}} \\{= \lbrack {29,000,000\mspace{14mu} {{psi}/{in}} \times 2.4656\mspace{14mu} {{in}^{4} \div 0.1415}\mspace{14mu} {lb}\text{-}{\sec^{2}/{in}} \times ( {88\mspace{14mu} {in}} )^{3}} \rbrack^{1/2}} \\{= {268.756\mspace{14mu} {radians}\mspace{14mu} {per}\mspace{14mu} {second}}}\end{matrix}$f _(f)=ω_(f)/2π=268.756/2π=42.774 cycles per second

-   -   The fundamental period of vibration of the panel without sand is

T _(f)=1/f _(f)=1/42.774 cps=0.0234 sec=23.379 ms

Weight of the composite steel panel with sand infill=2.1024 lbs/in×88inch length=185.01 lbs

-   -   The mass is the weight divided by gravity

m=185.01 lbs/386 in/sec²=0.4798 lb-sec²/in

The mass to stiffness ratio=0.4798 lb-sec²/in÷11.45 psi/in=0.0419lb-sec²/psi

-   -   The fundamental frequency of a uniformly loaded beam per the        Raleigh method is

$\begin{matrix}{\omega_{f} = {\prod^{2}\lbrack {{EI}\text{/}{ml}^{3}} \rbrack^{1/2}}} \\{= \lbrack {29,000,000\mspace{14mu} {{psi}/{in}} \times 2.4656\mspace{14mu} {{in}^{4} \div 0.4798}\mspace{14mu} {lb}\text{-}{\sec^{2}/{in}} \times ( {88\mspace{14mu} {in}} )^{3}} \rbrack^{1/2}} \\{= {146.026\mspace{14mu} {radians}\mspace{14mu} {per}\mspace{14mu} {second}}}\end{matrix}$f _(f)=ω_(f)/2π=146.026/2π=23.241 cycles per second

-   -   The fundamental period of vibration of the panel with sand        infill is

T _(f)=1/f _(f)=1/23.241 cps=0.0430 sec=43.0 ms

-   -   Thus in summary:    -   The ratio of fundamental period of the panel with sand to that        without sand is

Ratio=43.0 ms/23.379 ms=1.8393

-   -   The mass to stiffness ratio of the sand-filled panel to the        unfilled panel is

Ratio=0.0419 lb-sec²/psi÷0.0124 lb-sec²/psi=3.38

-   -   Thus it is seen that the fundamental periods of vibration are        directly related to the square root of the mass to stiffness        ratios of the two systems.    -   The addition of sand weighing 109 pounds per cubic foot to the        cavity in each panel increases the mass to stiffness ratio to        338 percent of the unfilled value and increases the fundamental        frequency of the panel to 184 percent of the unfilled value.    -   The test blast enclosure which was at a 20 foot standoff        distance had an initial positive deflection (inward) for a        duration of 23 ms and then a negative (outward) deflection for a        duration of 18 ms. These deflections resulted from the initial        positive blast pressure which had a duration of 4 ms and then a        negative blast pressure which had a duration of approximately 16        ms. Thus, it is seen that the total duration of the predominant        blast wave was significantly less than the fundamental period of        vibration of the sand filled wall panels.    -   A 6 inch thick reinforced concrete wall, having comparable        structural resistance to the measured blast pressures, has a        fundamental period of approximately 8.17 ms which is        approximately one-fifth the fundamental period computed for the        sand filled 3 inch thick composite steel panel.

The Particulate Material

The testing described above was done with a particulate materialcomprising dry silica sand having a density of approximately 109 poundsper cubic foot. It will be appreciated, however, that many types ofparticulate material could be utilized since the particulate material isnot being used for structural purposes, but instead is being used forits density and damping properties.

With regard to the sand types there are numerous types and uses of sandand specifications for the same. ASTM 33 fine aggregate sand and AASHTOM-6 gradation sands are examples of structural sands in common use.Structural sand is typically silica based sand rather than limestone orcoral based sand. But limestone or coral based beach sands can also beutilized for the present invention. Although a structural quality silicasand was utilized in the testing described, it will be appreciated thatstructural sand is not required for the present invention. Structuralquality sands are not required for the present invention because even ifinfused with a cementitious binder it is not required to attainstrength, such as are required for flexural concrete structures.

One alternative to the use of sand, is to use a low ratio cement to sandmixture having only enough cement to aid in the pumpability of themixture into the interior spaces of the walls and also to provide somemodest rigidity to the mixture to eliminate excessive outward pressureson the walls from the column of sand contained within the walls. Forexample, a cement to sand ratio in the range of from about 5% to about15%, and preferably about 10% is satisfactory for those purposes. Itwill be appreciated by those skilled in the art that such a low ratio ofcement does not produce a structural material and does not harden into astructural grout or concrete. The 1:10 cement mixture is contrasted tostructural mortar which would typically be a 1:3 ratio. The intent ofthe cement, if used at all, is to increase the internal friction of thesand cement matrix which would permit the walls of taller wall cavitiesto resist lateral pressures from the infill materials.

It will also be appreciated that, particularly in remote fieldoperations, any available native soil may be utilized as the particulatematerial and will, to a large degree, provide the benefits described.

The particulate material preferably has a density of at least 90 poundsper cubic foot, and more preferably in the range of from about 90 toabout 115 pounds per cubic foot.

The sand fill provides the inertial mass resistance to blast inducedaccelerations and a significant portion of the wall vibration dampingwhich, combined with the damping of the viscoelastic bonding adhesivesandwiched between the exterior and interior skins of the compositesteel structure, creates a ductile wall with outstanding blast resistingcharacteristics. The compound wall structure is unique in that asignificant portion of the kinetic energy from a non-penetrating impactis stored in the compound wall as potential energy which is slowlyreleased over time. The dynamic response of the composite wall to highimpulse waves of nearby blasts is attenuated to levels which result inflexural displacements and stresses below levels which would result ininjury to occupants or damage to the structure.

The apparatus is designed to resist not only the high impulse blastwaves of short standoff explosions but also the penetration by smallarms rounds and fragmentation of military ordinance. The sand infillserves to resist penetration by bullets, shrapnel, or fragmentingportions of adjacent structures which penetrate the exterior steel wall.

The Embodiments of FIGS. 14-21—Multi-Room Structure with Fabric TentCovering

Referring now to FIGS. 14-21, a multi-room building 300 is shown in planview. The multi-room building 300 includes six of the six-sidedstructures 100 which have been designated as 100A-100F. Smallerrectangular shaped modules 302 have been arranged at end locations toform baffled entryways 304 and 306 which prevent direct small arms firetrajectories into a protected interior corridor 308 and a protectedoccupied space 310. It will be appreciated by those skilled in the artthat an unlimited number of sizes and configurations of blast sheltermodules can be assembled to create large blast proof shelter assemblies.It will also be appreciated that such modules can be superimposed one ontop of the other to create multi-level blast resistant shelterassemblies.

FIG. 16 illustrates one manner in which the walls of the modules of FIG.14 may be anchored to a concrete slab 312. Also, as illustrated in FIG.16, it is possible to eliminate the lower rails from the framework whenthe module is going to be mounted directly on a concrete slab. Steelconcrete screw anchors 314 are inserted through heavy square steelwashers 316 and through prepunched holes in the center of the bottompanel end brackets 142 to engage the concrete slab 312. In addition toconcrete screw anchor 314, two smaller concrete screws are preferablyinstalled through prepunched holes 318 in the bottom end panel brackets142 into holes drilled into the concrete slab 312. It should be notedthat the concrete slab anchors must be installed on the walls before theinside wall cladding 144 is installed.

FIGS. 18 and 19 illustrate a roof plan view and perspective view,respectively, of the multi-room building 300 of FIGS. 14 and 15supporting a fabric tent covering 318 which is supported by means ofsteel support framing members 320, 322, 324 and 326 which are attachedto the shelter apparatus modules 100 and 302. Vertical support elements326 are attached to the open tops of the vertical tubes such as 110shown in FIG. 7 by means of light gauge steel tube sleeves like sleeve168 shown in FIG. 6, whose length of insertion is limited by a laser cuthalf moon stop 170. FIG. 20A shows an exterior side view of the fabrictent enclosure. FIG. 20B shows a section cut through the tented blastshelter assembly along lines 20B-20B of FIG. 20A. An exterior end viewis shown in FIG. 21. An attic space 328 is defined between the walls ofthe blast resistant shelter modules 100 and the fabric tent covering318. The attic space 328 permits air flow through screened vents nearthe skirt of the tent and to tent ridge vents or other type roof vents,permits air ducts, electrical communications connections and the like tobe placed in the attic space 328, and permits the attachment ofappurtenances such as vent structure 204 (see FIG. 17) on the roof. Italso provides a place for placement of sand bags 202 on the roof whererequired to provide roof terminal ballistics protection.

The Embodiment of FIGS. 22-24—Protected Spaces within Buildings

FIGS. 22 and 23 show the first and upper floors, respectively, in planview of a building 400, which may be existing or new, wherein variouslyconfigured blast shelter assemblies 100 are installed on interiorconcrete floor slabs 402 of the three floors. The blast resistant walls404 which are directly exposed to blast are filled with sand or sandcement mixture as previously described. The blast resistant walls 404are set back from exterior walls 406 so as to create ingress and egressspace 408 between the exterior walls 406 and the blast resistant walls404. This space 408 permits egress from the blast proof structures 100into the corridors 408 whereby alternate egress routes from the buildingother than a normal front entrance 410, elevator 330, or interiorstairway 332 are made available. This space 408 also permits access tothe blast face walls 404 for the installation of metal exterior blastshield 148.

FIG. 24 is a cross-sectional view of the three story building 400illustrating the arrangement of the shelter walls of the various blastproof shelter apparatus 100 within the building 400 at each floor. Itshould be noted that the load path for resistance to lateral forces onthe various modules 100 is provided by attachment of the tops of blastwalls to roof diaphragms 412 connected to interior shelter walls, andthe connection of the bottom of interior shelter walls to the concretefloor slabs such as 402 as illustrated in FIG. 16. It should be notedthat roof diaphragms 412 may extend either partially or fully over allthe blast resistant shelter assemblies 100.

It is also noted, that the interior blast proof walls may be constructedby an assembly of six-sided units 100 or by construction of individualblast proof walls constructed in accordance with the present inventionand laterally supported by lateral support walls, roof diaphragms andattachment to floor slabs.

The Embodiment of FIG. 26—A Perimeter Blast Resistant Curtain for aBuilding

FIG. 26 is an illustration of an exterior, blast resistant perimetercurtain wall 500 which is erected between the first floor concrete slab502 and the second floor framing 504 of a building 506.

The blast resistant perimeter curtain wall 500 is constructed in amanner similar to the walls of the apparatus 100 previously describedand is made up of a plurality of side by side panels 128. It will beappreciated that the panels 128 utilized in the perimeter curtain wall500 may be thicker, longer and constructed of heavier steel material andconnectivity than the similar panels 128 described previously withregard to the free-standing modules 100. However, the dynamicperformance of the composite, sand filled curtain wall blast panelswould be similar to that of the panels of the free-standing shelters 100previously described. Terminal ballistics protection is provided by anexterior steel sheet 506, an interior steel sheet 508, and theparticulate material 510. Connection of the bottom end panel bracket 142to the concrete slab floor 502 is identical to that described above withregard to FIG. 16. The top end panel bracket 140 is connected to a steelplate 512 in a manner similar to the connection of the top end brackets140 of free-standing apparatus 100 to the framework 102 of the apparatus100. The steel plate 512 has matching holes for screw attachments of endbrackets 140 and 142 and hole 514 for introducing sand or sand-cementmixture through end bracket holes 154 and is welded or bolted to thesecond floor framing 504.

Thus the building 506 may be described as a building 506 having afoundation 502 and a structural framework 504 extending upward from thefoundation 502. The blast resistant perimeter curtain wall 500 issupported from the framework 504 and at least partially defines aperimeter wall of the building 506. The curtain wall 500 is of modularconstruction including a plurality of side by side vertically orientedmetal panels 128, each panel having a hollow interior space having awidth and a height greater than its width, at least a majority of whichinterior space is filled with a particulate material such as sand or thelike.

As shown in FIG. 26, the building 506 is a multi-story building and theblast resistant perimeter curtain wall 500 spans the perimeter wall ofat least the first and second floors of the building.

Thus it is seen that the apparatus of the present invention readilyachieves the ends and advantages mentioned, as well as those inherenttherein. While certain preferred embodiments of the invention have beenillustrated and described for purposes of the present disclosure,numerous changes in the arrangement of parts may be made by thoseskilled in the art, which changes are encompassed within the scope andspirit of the present invention as defined by the appended claims.

1. A blast resistant shelter apparatus, comprising: a framework,including at least an upper metal rail; a plurality of metal panels,each panel having a C-shape cross-section defined by a central flat weband two channel arms on opposite sides of the central flat web, themetal panels being vertically mounted within the framework in side byside relationship to define a wall, each panel including an upper endplate; a metal interior wall cladding connected to the panels andspanning the channel arms of each panel to close the cross-sections ofthe panels to define an interior space of each panel; and wherein theupper metal rail and the upper end plate of each panel have aligned fillopenings defined therethrough for introducing a particulate materialinto the interior space of the associated panel.
 2. The apparatus ofclaim 1, further comprising: a metal exterior blast shield attached tothe central flat webs of the panels of the wall.
 3. The apparatus ofclaim 1, wherein: the adjacent channel arms of adjacent panels areattached to each other with screws.
 4. The apparatus of claim 3,wherein: the upper end plate of each panel is attached to the uppermetal rail of the framework with a viscoelastic adhesive and screws. 5.The apparatus of claim 1, wherein: each panel includes a lower end plateand the lower end plate of each panel has a drain opening definedtherein for draining the particulate material from the interior space ofthe associated panel.
 6. The apparatus of claim 5, wherein: theframework includes a lower metal rail, the lower metal rail having aplurality of openings defined therein aligned with the drain openings ofthe panels, for draining the particulate material.
 7. The apparatus ofclaim 1, wherein the panels have a stiffness and the interior space ofeach panel has a volume such that if the interior space were filled withparticulate material having a density of approximately 109 pounds percubic foot, a mass to stiffness ratio of the panels would be in therange of from about 0.03 lb-sec²/psi to about 0.05 lb-sec²/psi.
 8. Theapparatus of claim 1, wherein: each panel includes two channel fingersextending toward each other from the two channel arms; and the interiorwall cladding is attached to the channel fingers of each panel.
 9. Theapparatus of claim 1, wherein: the framework defines a six-sidedstructure having four walls, each of the four walls including aplurality of said metal panels; the framework includes the metal upperrail and a metal lower rail for each of the four walls; each panelincludes a lower end plate; and the lower end plates of each panel ofthe four walls and the lower metal rail of each wall have aligned drainopenings defined therethrough to allow particulate material to drainfrom the interior spaces of the panels when the structure is lifted offa ground surface to thereby reduce a weight of the structure fortransport and re-location of the structure.
 10. The apparatus of claim9, wherein each of the panels of each wall is attached to the associatedupper and lower metal rails of the framework by a visco-elastic adhesiveand screws and to at least one adjacent panel by screws.
 11. Theapparatus of claim 9, in combination with at least one additional suchsix-sided structure to define a multi-room building; and a tentenclosure arranged over the structures to define an attic space forlocating utilities extending to the building.
 12. The apparatus of claim1, located within a building interior and connected to at least onelaterally extending support wall of the structure and having theinterior space of the panels filled with particulate material to atleast partially define a protected space within the building.
 13. Theapparatus of claim 12, wherein the upper rail of the framework isattached to a structural ceiling diaphragm.
 14. The apparatus of claim1, hung on an exterior of a building and having the interior space ofthe panels filled with particulate material to define a blast resistantcurtain for the building.
 15. The apparatus of claim 1, furthercomprising a particulate material received in the interior space of eachpanel of the wall, the particulate material having a density in therange of from about 90 pounds per cubic foot to about 115 pounds percubic foot.
 16. The apparatus of claim 15, wherein the particulatematerial comprises sand.
 17. The apparatus of claim 15, wherein theparticulate material comprises a low ratio cement to sand mixture havinga cement to sand ratio in a range of from about 5% to about 15%.
 18. Ablast resistant shelter apparatus, comprising: a framework including atleast an upper rail; a plurality of panels, each panel having anenclosed interior space, the panels being vertically mounted within theframework in a side by side relationship and attached to each other andthe upper rail to define a wall; and a particulate material received inthe interior space of each panel of the wall, the wall having a mass tostiffness ratio in a range of from about 0.03 lb-sec²/psi to about 0.05lb-sec²/psi.
 19. The apparatus of claim 18, wherein the panels areattached to adjacent panels with screws and to the upper rail byadhesive and screws.
 20. The apparatus of claim 19, wherein the panelsand the upper rail are constructed of steel.
 21. The apparatus of claim18, wherein the particulate material comprises primarily sand.
 22. Theapparatus of claim 21, wherein the particulate material has a density ina range of from about 90 to about 115 pounds per cubic foot.
 23. Theapparatus of claim 18, wherein the particulate material comprises a lowratio cement to sand mixture having a cement to sand ratio in a range offrom about 5% to about 15%.
 24. The apparatus of claim 18, wherein: theframework and an upper end of each panel have aligned fill openingstherein, for filling the panels with the particulate material; and theframework and a lower end of each panel have aligned drain openingstherein for draining the particulate material from the wall.
 25. Theapparatus of claim 18, wherein the framework defines a six-sidedstructure having four such walls.
 26. The apparatus of claim 25, incombination with at least one additional such six-sided structure todefine a multi-room building; and a tent enclosure arranged over thestructures to define an attic space for locating utilities extending tothe building.
 27. The apparatus of claim 18, erected within a buildinginterior and connected to at least one laterally extending support wallof the structure and connected to a structural ceiling member of thestructure to at least partially define a protected space within thebuilding.
 28. The apparatus of claim 18, mounted on an exterior of abuilding to define a blast resistant curtain for the building.
 29. Ablast resistant shelter apparatus, comprising: a plurality of six-sidedroom structures arranged in a pattern to define a multi-room building;each of the room structures having four room walls; each of the roomwalls including a plurality of panels vertically mounted in a side byside relationship to define the respective room wall, each panel havingan enclosed interior space; a particulate material received in theinterior spaces of the panels of at least some of the room walls to makethose particulate filled room walls blast resistant; and a tentenclosure arranged over the free-standing structure to define an atticspace of the building.
 30. The apparatus of claim 29, wherein: withinthe pattern some of the room walls of adjacent room structures face eachother to define interior room walls of the building, and the remainingroom walls define exterior room walls of the building; and substantiallyall of the exterior room walls of the building are filled with theparticulate material to comprise said blast resistant room walls. 31.The apparatus of claim 29, wherein: each of the panels is made of steelsheet and has a C-shape cross-section defined by a central flat web andtwo channel arms on opposite sides of the central flat web, with a steelsheet cladding spanning the channel arms to close the cross-section todefine the interior space of the panel.
 32. The apparatus of claim 31,further comprising: an exterior sheet steel blast shield attached to thecentral flat webs of the panels of at least some of the room walls. 33.The apparatus of claim 29, wherein: the panels of the particulate filledroom walls each have an upper end having a fill opening defined thereinfor introducing the particulate material into the interior space of thepanel, and a lower end having a drain opening therein for draining theparticulate material from the panel.
 34. The apparatus of claim 29,further comprising building utilities located in the attic space.
 35. Ablast resistant shelter apparatus, comprising: a building having aplurality of structural exterior walls; a blast resistant interior walllocated within the building and spaced inwardly from the exterior walls,the interior wall having a hollow wall space and having a majority ofthe hollow wall space filled with a particulate material having adensity of at least 90 pounds per cubic foot; and at least one laterallyextending interior support wall connected to the blast resistantinterior wall.
 36. The apparatus of claim 35, further comprising: astructural ceiling attached to the blast resistant interior wall. 37.The apparatus of claim 35, further comprising: a plurality of additionalblast resistant interior walls arranged with the first blast resistantwall to define a blast resistant area within the building.
 38. Theapparatus of claim 35, wherein: the building comprises at least a firstfloor and a second floor located above the first floor; and a pluralityof said blast resistant interior walls are located on each of said firstand second floors to define a blast resistant zone on each floor.
 39. Ablast resistant shelter apparatus, comprising: a building having afoundation and a structural framework extending upward from thefoundation; and a blast resistant perimeter curtain supported from theframework and at least partially defining a perimeter wall of thebuilding, the curtain being of modular construction and including aplurality of side-by-side vertically oriented metal panels, each panelhaving a hollow interior panel space having a width and a height greaterthan said width, at least a majority of which space is filled with aparticulate material.
 40. The apparatus of claim 39, wherein adjacentpanels are attached to each other with an adhesive.
 41. The apparatus ofclaim 39, further comprising: a steel sheet exterior blast shieldattached to said panels.
 42. The apparatus of claim 39, wherein: theframework defines at least a first floor and a second floor locatedabove the first floor; and the blast resistant perimeter curtain spansthe perimeter wall of at least the first and second floors.